The present invention relates to vertically-raisable doors for industrial use to insulate workshops, stores, etc. from drafts and to protect their temperature and sound-level environments relative to other workshops, stores, etc. or relative to the outside, and it relates more particularly to "curtain-type" doors whose main component for closing a door-bay is a curtain which may be flexible and which is raised to be folded up in the top portion of the door, or which may be constituted by rigid panels which rise above the door bay to open the door. The edges of such a curtain, or at least the ends of reinforcing bars that may also constitute hinges of such a curtain are guided in lateral slideways received in or formed by the vertical lateral uprights of a door-frame which also includes a top cross-member, thereby presenting an assembly of adequate mechanical strength. The top cross-member may house mechanical components such as a motor, an end-of-stroke contact, a wind-up shaft, electrical apparatus, etc.
During the up and down movements of the door, the slideways must be relatively wide, at least over a certain height thereof, in order to allow the curtain to move without restriction. However, when the door is in its closed or down position, the curtain must remain as stationary as possible in a vertical plane, preferably against one of the edges of each slideway, namely the edge against which wind pressure urges it most often, in order to eliminate both disagreeable noise and vibration that may damage the equipment. That is why the lateral slideways for the edges of such curtains and for the ends of their reinforcing bars have a bottom portion of narrower section that matches the thickness of the curtain or the thickness of the reinforcing bars.
Since it is not desirable, economically speaking, to make slideways of tapering width, this means that filler components are placed in the bottom portions of such slideways to reduce the available inside width thereof progressively. Such components may be made of welded sheet metal, of molded plastic, or in the form of a solid block made of wood, metal, plastic, etc. It often turns out that the remedy is worse than the original problem. In combatting undesirable vibration and noise, various causes such as gusts of wind, or inaccuracy in assembly or in manufacture of the door structure can lead to jamming such that when the curtain is raised it is torn and destroyed.
An object of the invention is to provide a device that enables the curtain to be properly positioned when down, while avoiding jamming.